SYSTEM AND METHOD FOR MULTILATERATING A POSITION OF A TARGET USING MOBILE REMOTE RECEIVING UNITS

• US 20070247368A1
• Filed: 04/17/2007
• Published: 10/25/2007
• Est. Priority Date: 04/21/2006
• Status: Active Grant

• Current Assignee: SAAB Cars
• Original Assignee: Sensis Pty Limited (Telstra Group Ltd.)
• Inventors: Wu, Haoyun
• Granted Patent: US 7,847,734 B2
• Time in Patent Office: Days
• US Class Current: 342/465
• CPC Class Codes: G01S 5/0284 Relative positioning
• CPC Class Codes: G01S 5/0289 of multiple transceivers, e.g. in ad hoc networks
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial

Abstract

A method of multilaterating the position of a target, including the steps of deploying a plurality of time synchronized receiving units in a network that allows the receiving units to communicate with a central processor; receiving a target signal from the target at each receiving unit; determining a time of arrival for the target signal at each receiving unit; determining position data for each receiving unit at the time when the target signal is received at each respective receiving unit; and using the time of arrival and position data for each receiving unit to determine the position of the target by multilateration. A system for carrying out the method is also disclosed.

Claims

1. A method of multilaterating the position of a target, comprising the steps of:

deploying a plurality of time synchronized receiving units in a network that allows the receiving units to communicate with a central processor;

receiving a target signal from the target at each receiving unit;

determining a time of arrival for the target signal at each receiving unit;

determining position data for each receiving unit at the time when the target signal is received at each respective receiving unit; and

using the time of arrival and position data for each receiving unit to determine the position of the target by multilateration.

2. The method of claim 1, wherein the step of determining position data comprises each receiving unit determining its own position.

3. The method of claim 2, wherein each receiving unit determines its own earth coordinate position.

4. The method of claim 3, wherein each receiving unit includes a GPS receiver to determine its own earth coordinate position.

5. The method of claim 4, wherein each receiving unit uses GPS signals for time synchronization.

6. The method of claim 1, wherein a first receiving unit includes a GPS receiver to determine its own earth coordinate position, and the position data for each remaining receiving unit is determined relative to the first receiving unit.

7. The method of claim 1, wherein a first receiving unit includes a clock that uses GPS signals for time synchronization.

8. The method of claim 7, wherein each remaining receiving unit includes a clock that is synchronized to the clock of the first receiving unit.

9. The method of claim 1, wherein each receiving unit determines its own position relative to at least another one of the receiving units, and the position of the target is determined relative to the positions of the receiving units.

10. The method of claim 1, wherein at least one receiving unit is capable of determining direction of arrival (DOA) of said target signal at said at least one receiving unit.

11. The method of claim 10, wherein said direction of arrival (DOA) data is used to assist in multilaterating the position of said target signal source.

12. The method of claim 1, further comprising deploying relay stations to facilitate communication within the network.

13. The method of claim 12, wherein the relay stations are mobile surface or air units that do not receive the target signal from the target.

14. The method of claim 1, wherein the receiving units are non-surveyed, mobile surface or air units.

15. The method of claim 1, wherein the network comprises a satellite communications link.

16. The method of claim 1, wherein the network comprises a microwave communications link.

17. The method of claim 1, wherein at least one of the receiving units includes at least one sensor for detecting a physical condition of the receiving unit.

18. The method of claim 17, wherein said sensor is at least one of a speedometer, compass, accelerometer, gyroscope and altimeter.

19. A method of time synchronizing a plurality of receiving units in a multilateration system, comprising the steps of:

forming a communications network between the plurality of receiving units, the communications network supplying data between receiving units and a central processor;

transmitting a message from a first receiving unit to at least one other receiving unit to initiate time synchronization between a clock in the first receiving unit and clocks in the at least one other receiving unit;

receiving, at the first receiving unit, a response message from the at least one other receiving unit; and

transmitting a reply message from the first receiving unit to the at least one other receiving unit, wherein the reply message contains at least one of (i) a time of receipt of the response message at the first receiving unit, and (ii) a time of transmission of the reply message from the first receiving unit, whereby the at least one other receiving unit uses the messages from the first receiving unit to synchronize the clock in the at least one other receiving unit to the clock in the first receiving unit.

20. The method of claim 19, wherein at least one of the messages contains a time quality indicator, and said method further comprises the step of determining which receiving unit has the clock with the highest quality indicator.

21. The method of claim 19, wherein the reply message contains the time of receipt of the response message at the first receiving unit and the time of transmission of the reply message from the first receiving unit.

22. The method of claim 19, wherein, after the clock in said at least one other receiving unit is synchronized to the clock in the first receiving unit, the steps are repeated for yet another receiving unit with respect to said at least one other receiving unit.

23. The method of claim 19, wherein at least one of the receiving units includes at least one sensor for detecting a physical condition of the receiving unit.

24. The method of claim 23, wherein said sensor is at least one of a speedometer, compass, accelerometer, gyroscope and altimeter.

25. A method of time synchronizing a plurality of receiving units in a multilateration system comprising the steps of:

forming a communications network between the plurality of receiving units, the communications network supplying data between the receiving units and a central processor;

transmitting a message from a second receiving unit to a first receiving unit;

receiving, at the second receiving unit, a reply message from the first receiving unit, wherein the reply message contains at least one of (i) a time of receipt of the message at the first receiving unit, and (ii) a time of transmission of the reply message from the first receiving unit, whereby the second receiving unit uses the reply message from the first receiving unit to synchronize a clock in the second receiving unit with a clock in the first receiving unit.

26. The method of claim 25, further comprising the step of determining whether the clock in the first receiving unit is of a higher quality than the clock in the second receiving unit before synchronizing the clock in the second receiving unit to the clock in the first receiving unit.

27. The method of claim 25, wherein the reply message contains the time of receipt of the message at the first receiving unit and the time of transmission of the reply message from the first receiving unit.

28. The method of claim 25, wherein, after the clock in the second receiving unit is synchronized to the clock in the first receiving unit, the steps are repeated for a third receiving unit with respect to the second receiving unit.

29. The method of claim 25, wherein at least one of the receiving units includes at least one sensor for detecting a physical condition of the receiving unit.

30. The method of claim 29, wherein said sensor is at least one of a speedometer, compass, accelerometer, gyroscope and altimeter.

31. A method of multilaterating the position of a target, comprising the steps of:

deploying a plurality of time synchronized receiving units in a network that allows the receiving units to communicate with a central processor;

equipping at least one receiving unit with a GPS receiver;

transmitting signals between the receiving units to determine position data for each receiving unit;

receiving a target signal from the target at each receiving unit;

determining a time of arrival for the target signal at each receiving unit; and

using the time of arrival and position data for each receiving unit to determine the position of the target by multilateration.

32. The method of claim 31, wherein each receiving unit is equipped with a GPS receiver so that position data can be determined for each receiving unit.

33. The method of claim 32, wherein the signals transmitted between the receiving units are used to determine range data between the receiving units, whereby the GPS position data for each receiving unit is supplemented by the range data to determine more precise position data for each receiving unit.

34. The method of claim 31, wherein at least one of the receiving units includes at least one sensor for detecting a physical condition of the receiving unit.

35. The method of claim 34, wherein said sensor is at least one of a speedometer, compass, accelerometer, gyroscope and altimeter.

36. The method of claim 31, wherein the signals transmitted between the receiving units are used to determine range data between the receiving units, whereby the GPS position data for at least one of the receiving units is supplemented by the range data to determine more precise position data for the at least one of the receiving units.

37. The method of claim 32, wherein at least one of the receiving units includes at least one sensor for detecting a physical condition of the receiving unit.

38. The method of claim 37, wherein said sensor is at least one of a speedometer, compass, accelerometer, gyroscope and altimeter.

39. The method of claim 31, wherein at least one of the receiving units is equipped with a multi-sector antenna or antenna array to determine the direction of arrival (DOA) of received signals.

40. The method of claim 39, further comprising determining the direction of arrival (DOA) of the signals transmitted between the receiving units at the at least one receiving unit equipped with a multi-sector antenna or antenna array and supplementing the GPS position data for at least one of the receiving units with the direction of arrival (DOA) data to determine more precise position data for the at least one of the receiving units.

41. The method of claim 34, further comprising determining relative speed data for at least one receiving unit and supplementing the GPS position data for at least one of the receiving units with the relative speed data to determine more precise position data for the at least one of the receiving units.

42. The method of claim 32, wherein at least one of the receiving units is equipped with a multi-sector antenna or antenna array to determine the direction of arrival (DOA) of received signals.

43. The method of claim 42, further comprising determining the direction of arrival (DOA) of the signals transmitted between the receiving units at the at least one receiving unit equipped with a multi-sector antenna or antenna array and supplementing the GPS position data for at least one of the receiving units with the direction of arrival (DOA) data to determine more precise position data for the at least one of the receiving units.

44. The method of claim 37, further comprising determining relative speed data for at least one receiving unit and supplementing the GPS position data for at least one of the receiving units with the relative speed data to determine more precise position data for the at least one of the receiving units.